The present invention relates to a distributed constant type electromagnetic delay line for handling a super high speed signal having a rise time which is equal to or less than one nanosecond, and in particular relates to an improvement of such a distributed constant type electromagnetic delay line in which an electroconductive strip and a ground plane oppose each other with a dielectric layer interposed therebetween.
A type of delay line is shown in FIGS. 17 and 18 of the accompanying drawings in front view and in side on view respectively. This delay line, which it is not intended hereby to admit as prior art to the present application except to the extent otherwise required by applicable law, and which was developed in the workshops of the assignee of the present application by an inventive entity under obligation to assign any intellectual property rights arising therefrom to the assignee of the present application, has a flattened and elongated bobbin 5 which is formed by covering the outer circumference of a ground plane 1 formed in the shape of a plate strip with dielectric material 3, and an electroconductive strip 7 is formed by winding a single layered solenoid in a spaced manner around the outer circumference of the bobbin 5 so that this electroconductive strip 7 opposes the ground plane 1. The electroconductive strip 7 in the drawings makes use of a plurality of individual electroconductive strips 9 which are in the shape of fine strips, and these are connected in series so as to form a single solenoid layer.
Such an electromagnetic delay line can produce favorable delay properties with respect to super high speed signals, and it is suitable for compact design, but according to studies performed by the present inventive entity it has been discovered that there remains further room for improvement.
Specifically, since the bobbin 5 in the above outlined construction is made by covering the outer circumference of the ground plane 1 with the dielectric material 3 having a constant thickness, it is necessary to use a special metallic die for forming the bobbin 5.
However, in general there are required a variety of electromagnetic delay lines with various delay times and impedance properties, and therefore, in order to make an electromagnetic delay line having desired properties, it is necessary to change the width W and the thickness T of the bobbin 5.
However, when the dimensions of the bobbin 5 are changed, the metallic die for forming it is naturally required to be changed, and this entails a need for stocking a large number of metallic dies, which in turn increases the necessary investment required, and makes the production process more complex. Further, in making actual electromagnetic delay lines, the forming of electroconductive strips 7 on such a variety of bobbins 5 requires various production expedients and ingenuities.